thanks!
I do know how to solve the equation however i can't get the answer correct..

My book says that if we use 3 there's no solution but i can't seem to continue with -2 either...

thanks

for a= -2

Edit : here you have :

two same equations :

so you have

so you have one equation with 2 unknowns....

you have infinity of the solutions and equations are dependent (meaning for each new x or y you have another solution for that second unknown)

for a = 3

Edit : here you have :

now here it's easy to see there are no solutions because you have ones that x+y = 2 and another saying that x+y = 4.5 which cant be true for the both of the equations

Edit: hm... this is moved to the university sub forum ( I think it was in pre-algebra at the start .... perhaps i'm wrong but ... ) , well if here you must show that based on determinants of that system you don't have / have solutions and if you have why and which , and if don't why ... and so on ... there are few cases by which you conclude this